The invention relates to image registration, and particularly to registration of distorted, rotated, translated and/or differently scaled images.
U.S. patent application Ser. No. 12/959,089, filed Dec. 2, 2010, by the same assignee describes an image acquisition device having a wide field of view that includes a lens and image sensor configured to capture an original wide field of view (WFoV) image with a field of view of more than 90°. The device has an object detection engine that includes one or more cascades of object classifiers, e.g., face classifiers. A WFoV correction engine may apply rectilinear and/or cylindrical projections to pixels of the WFoV image, and/or non-linear, rectilinear and/or cylindrical lens elements or lens portions serve to prevent and/or correct distortion within the original WFoV image. One or more objects located within the original and/or distortion-corrected WFoV image is/are detectable by the object detection engine upon application of the one or more cascades of object classifiers.
U.S. patent application Ser. No. 13/028,203, filed Feb. 15, 2011, by the same assignee describes a technique to determine a measure of frame-to-frame rotation for a sequence of two or more images. A global XY alignment of a pair of frames is performed. Local XY alignments in at least two matching corner regions of the pair of images are determined after the global XY alignment. Based on differences between the local XY alignments, a global rotation is determined between the pair of frames.
U.S. patent application Ser. No. 13/020,805, filed Feb. 3, 2011, by the same assignee describes an autofocus method that includes acquiring multiple images each having a camera lens focused at a different focus distance. A sharpest image is determined among the multiple images. Horizontal, vertical and/or diagonal integral projection (IP) vectors are computed for each of the multiple images. One or more IP vectors of the sharpest image is/are convoluted with multiple filters of different lengths to generate one or more filtered IP vectors for the sharpest image. Differences are computed between the one or more filtered IP vectors of the sharpest image and one or more IP vectors of at least one of the other images of the multiple images. At least one blur width is estimated between the sharpest image and the at least one of the other images of the multiple images as a minimum value among the computed differences over a selected range. The steps are repeated one or more times to obtain a sequence of estimated blur width values. A focus position is adjusted based on the sequence of estimated blur width values.
U.S. patent application Ser. No. 13/077,891, filed Mar. 31, 2011, by the same assignee describes a technique of enhancing a scene containing one or more off-center peripheral regions within an initial distorted image captured with a large field of view. The technique includes determining and extracting an off-center region of interest (hereinafter “ROI”) within the image. Geometric correction is applied to reconstruct the off-center ROI into a rectangular or otherwise undistorted or less distorted frame of reference as a reconstructed ROI. A quality of reconstructed pixels is determined within the reconstructed ROI. Image analysis is selectively applied to the reconstructed ROI based on the quality of the reconstructed pixels.
U.S. patent application Ser. No. 13/078,970, filed Apr. 2, 2011, by the same assignee describes a technique of enhancing a scene containing one or more off-center peripheral regions within an initial distorted image captured with a large field of view. The technique includes determining and extracting an off-center region of interest (hereinafter “ROI”) within the image. Geometric correction is applied to reconstruct the off-center ROI into a rectangular or otherwise undistorted or less distorted frame of reference as a reconstructed ROI.
U.S. patent application Ser. No. 13/084,340, filed Feb. 15, 2011, by the same assignee describes a technique of enhancing a scene containing one or more off-center peripheral regions within an initial distorted image captured with a large field of view. The technique includes determining and extracting an off-center region of interest (hereinafter “ROI”) within the image. Geometric correction is applied to reconstruct the off-center ROI into a rectangular or otherwise undistorted or less distorted frame of reference as a reconstructed ROI. A quality of reconstructed pixels is determined within the reconstructed ROI. One or more additional initially distorted images is/are acquired, and matching additional ROIs are extracted and reconstructed to combine with reduced quality pixels of the first reconstructed ROI using a super-resolution technique to provide one or more enhanced ROIs.
Each of these patent applications is hereby incorporated by reference into the detailed description as describing alternative embodiments and techniques that may be used in combination with one or more features of embodiments described herein.